1898.] NATURAL SCIENCES OF PHILADELPHIA. 165 



THE MUSCIDiE COLLECTED BY DR. A. DONALDSON SMITH IN SOMALI 



LAND. 



BY GARRY DE N. HOUGH, M. D. 



One cannot offer for publication a paper on Muscidse in which 

 species are described as new without a certain amount of misgiving. 

 So many descriptions of Muscidse have been published that I fear I 

 may have overlooked some, and that I may have added to the 

 already too long list of synonyms. I can only say that I have con- 

 scientiously tried to avoid this. My descriptions are long, but the 

 resemblances between the Muscidse are so close, that it is essential 

 to describe new species at length if they are ever to be recognized 

 by subsequent students. If any of the species described as new are 

 already known, I shall be very glad to be informed of it and to 

 publish the synonymy. 



Considerable space has been given to the bristles of the head, 

 and, as I have felt obliged to introduce some new names, my de- 

 scriptions must be prefaced by a few remarks on these bristles. 



Bristles of the Head. — The central feature of the muscid face is 

 the frontal suture, which, taken as a whole, has the shape of an in- 

 verted U, the arms making with one another more or less of an 

 angle. 



If we draw a line across the face tangent to the convexity of this 

 suture, then the part of the face dorsad of this line and between the 

 eyes is the front. The fraut is distinctly divided into three parts, 

 a median (the frontal vitta), and two lateral (the geno vertical 

 plates). The boundary lines between the vitta and the geno-verti- 

 cal plates are marked by rows of bristles (usually one row on each 

 side of the vitta), which are inserted in a dorso-ventral line from a 

 point on a level with the anterior ocellus to the ventral border of 

 the front. These are the frontal bristles. They are in two groups 

 which I call the ascending frontal and the trans-frontal. The 

 ascending frontal, from one to four in number, are the most dorsad 

 of the frontal bristles. If more than one is present, the most dor- 

 sad is the largest, and each succeeding one is smaller (usually much 

 smaller) than its dorsal neighbor. They are curved dorsad, caudad 

 and more or less laterad, and are parallel to one another. 



